Package dyeing



Patented Fel a 29, 1944 PACKAGE DYEING Willard H. Watkins, Bound. Brook, Ormond W. Clark, Ridgefleld, and Wilbur A. Swanson, New

Brunswick, N; J., assignors to American Cyanamid Company, New York, N. Y., a corporation of. Maine No Drawing. Application January 24, 1940,

Serial No. 315,330

6 Claims.

Thisinvention relates to package dyeing and more particularly to an improved process ofpackage dyeing which permits the dyeing of relatively coarse yarns.

In-the past, package dyeing has been used extensively for the large scale dyeing of yarn in package form. In spite of the many practical advantages of this process; there have been certain drawbacks. One of the most serious drawbacks is the production of cross-overs," that is, light spots where two strands of yarn cross over each other' and where, in the ordinaryprocesses, dye penetration may not be complete. The diillculties involved in cross-overs increase very rapidly with the coarseness of the yarn, so much so. that for practical operation it has up to now been considered undesirable to dye yarns with a large number of strands. This has necessitated dyeing with a single strand yarn or two strands'and then twisting these together after the dyeing to obtain the coarser yarns which are in demand for many purposes. difliculty involved in the formation of cross-overs. although practically the product is of suilicient uniformity that it is commercially acceptable.

Essentially the procedure formerly used in package dyeing involves the following steps: The

packages are placed in the machine,'wet out with water or a solution of a suitable wetting agent in water, then the dyebath is pumped through the package with or without reversals of direction as the operator chooses. After dyeing the packages are rinsed out with water and then the dye is set by a suitable oxidation. In the case of a vat dye, it is set by chemical oxidation using sodium pervborate. The oxidizing agent is then washed out and after soaking and rinsing the yarn is dried.

- Considerable eflorts have been directed to making the wetting out more complete as it was thought that the more complete the wetting out, the more level the dyeing, and hence the less tendency to cross-over or to light dyeing on the inside of the package. This has led to experiments with soaps and surface tensionreducing agents the poweriul wetting agent type, but it has not been possible to remove defects in uniform dye penetration and the cross-over problem still remained.

The present invention is based on the surprising discovery that if the'packages are not wet out at all before the dye liquor is circulated, much.

more uniform penetration is obtained and crossover difliculties areentirely eliminated, or so greatly reduced that yarns of twelve strands or more can be dyed eflectively. We do not know Even with line yam there is somejust why this improved result is obtained, in spite 'of the fact that it goes contrary to the procedures I which have been in regular use.

.The invention is therefore not intended to be limited to any theory of action. We believe, however, that at least one factor may be the capillarity-of dry yarn which is of course destroyed if it is given a preliminary wetting out with water or a solution of a wetting agent in water.- It is possible that this is the only or the main factor in the improved results of the present invention. The phenomenon is however not readily susceptible to analysis of the different factors which are involved, and it is possible that other factors may be present and may be of major importance. theory is advanced purely as a possible explanation which seemed reasonable from theinformaloss of other desirable procedures in 'the process. It is an' advantage of thepresent"invention that.

it may be. used in conjunction .with other features of package dyeing which are of importance. Thus, for example, it is desirable to incorporate a soap in the dyeing liquor in order to prevent or minimize deposition of color scum on the inside or the outside of the packages. The use of dry packages in the process of the present invention venting scum formation also produces an even' more uniform dyeing in a shorter time in the I present process.

Procedural details will vary with different dyes but as a subsidiary feature 'of the present invention we have found that with vat dyes which are capable of withstanding fairly high solution tem-- peratures, it is desirable to operate at .a temperature higher than'that which is normally recommended in the usual package dyeing procedure. Thus instead of. the normal -160 F. temperature which is standard practice in the The above- It is a further advantage of theindustry, we have found that with vat dyes which are capable of withstanding higher temperatures, that more rapid and even more level and complete dyeing is obtainable by carrying out the dye operation at about 190 F Particularly we have found it advantageous to bring up the temperature of the dyebath rapidly to 190 F. and then maintain it at this temperature as we find somewhat better results are obtained by quickly heating up the liquor rather than employing a more gradual rise in temperature. Results will vary from dye to dye, and of course with dyes sensitive to such high temperatures, it is desirable to follow the somewhat lower temperatures which are more customary. It is an advantage of the present invention that improvements are obtained at ordinary temperatures and that these improvements are even more marked at higher temperatures where the particular dye can. withstand such treatment. With heat stable dyes, therefore, we prefer to operate at the higher temperatures although the invention is not limited thereto.

The invention will be described in greater de- I tail in connection with the specific example setting out the dyeing procedure with a heat stable vat dye. The example is intended to be purely illustrative and not to limit the invention to the details therein set forth.

Example A Smith drum package dyeing machine having 100 lbs. capacity was filled with a dye bath obtained by dispersing 2 lbs. of Calcoloid Pink FFD Double Powder (as prepared under U. S. Patent 2,090,511, issued August 17, 1987), in two gallens of water at 120 F. to which was added 3 lbs. of olive oil soap dissolved in water and. sufficient water added to make up the proper volume. The manifold of the machine was loaded with dry packages of twelve-strand cotton yarn, lowered into the machine, and the pump started circulating dye liquor from the outside to the inside of the packages. The temperature was brought up at once to 190 F. and at the same time 8 lbs. of caustic soda and 7 lbs. of sodium hydrosulfite was added. The pump was run circulating dye liquor from the outside to the inside of the packages for minutes, then the flow was reversed and run for 15 minutes, and then again reversed, the temperature being maintained at 190 F. during the whole time. The liquor was then pumped off, the packages flushed with water, avoiding the entrance of air, until they were clean. Then 2 lbs. of sodium perborate dissolved in water was added, heated to 130 F. and the machine run at this temperature for 15 minutes, whereupon the temperature was raised to the boil and 4 oz. soda ash and 2 lbs. of soap were added, and the machine run at the boil for 15 minutes. lhis was followed by thorough rinsing, the packages were removed and the yarn dried. An excellent level dyeing resulting without difllculty from cross-overs.

In a similar manner rayon or other yarns can I be dyed and q if desired, finer yarn can be dyed with even greater facility. In the case of heat sensitive dyes the operation may be carried out at -160 F. without material change in the other conditions.

The. primary feature of the present invention, that is to say, using a dry package, overcomes to a very large extent the dimculties encountered with cross-overs, but only when combined with pigment dyeing rather than dyeing with a reduced vat is this advantage obtained without a corresponding loss in levelness of dyeing between the outside and inside of the package. The combination of dry package with pigment dyeing particularly when using soap obtains. all of the advantages of the present invention without any disadvantage and is the preferred procedure.

In the preferred pigment dyeing process of the present invention the dyeing is efiectedby the ordinary pigment dyeing methods, that is to say, the unreduced vat dyestuff in fine dispersion is circulated through the goods until it is distrubuted therein, and is then subjected to reduction to the leuco form, followed by oxidation on the fiber.

What we claim is: I

1. A method of package dyeing cellulosic yarn which comprises introducing the packages into a package dyeing machine dry, circulating an aqueous dye bath containing a finely dispersed unreduced vat dyestufli through the packages, adding alkali and reducing agents. to the bath to reduce the vat dyestufl to the leuco form, circulating the bath through the packages, and oxidizing the leuco dyestufi on the yarn.

2. A process according to claim 1 in which the temperature of the machine is maintained about F.

3. A method according to claim 1 in which the yarn in the packages is a multi-strand yarn having a number of strands such that package dyeing with pre-wetting of the packages will result in the production of cross-overs.

4. A method of package dyeing cellulosic yarn which comprises introducing the packages into a package dyeing machine dry, circulating an aqueous dyebath containing a finely dispersed unreduced vat dyestuif in a dye bath containing soap through the packages, adding alkali and reducing agents to the bath to reduce the vat dyestuff to the leuco form, circulating the bath through the packages, and oxidizing the leuco dyestufl on the yarn.

5. A process according to claim 4 in which the temperature of the machine is maintained about 190 F.

6. A method according to claim 4 in which the yarn in the packages is amulti-strand yarn having a number of strands, such that package dyeing with prewettlng of the packages will result in the production of cross-overs.

WILLARD H. WATKINS. ()RMOND W. CLARK. WILBUR A. SWANSON. 

